1. Technical Field
The present invention relates to a film forming device, a film forming method, and a method for manufacturing an electronic appliance.
2. Related Art
It is known that there are methods for forming films composed with high polymer compounds, such as arranging a solution, in which the high polymer compounds are dissolved in a solvent, utilizing an inkjet method on a substrate, thereafter causing the solvent to evaporate from the arranged solution. It is relatively easy to produce films with high polymer compounds.
In contrast, if the same method described above, which applies to high polymer compounds, is used for compounds with a low molecular weight (hereafter referred to as ‘low-molecular compounds’) that are not categorized as high polymer compounds, the low-molecular compounds film is not formed, and the particles thereof are separated out on the substrate. This is caused since the cohesive force between the low-molecular compounds is significantly larger than the bonding power between the low-molecular compound and the substrate.
The low-molecular compounds are materials with a high crystallizability, as their cohesive force is strong, which carries a great advantage in functionalities such as conductivity. Therefore, a method that allows film formation of low-molecular compounds is awaited.
When droplets are arranged on substrates by discharging solvents with the inkjet method, the uneven partial pressure of gas in the vicinity of the droplets causes a distortion of the droplets. Consequently, the droplets tend to shift toward the locations with a higher partial pressure. Here, the gas includes the same component as that of a solvent of the solution in the droplets. This shifting of droplets tends to occur particularly when discharging a solution with low-molecular compounds, in which their bonding with the substrate is weak, resulting in difficulties in forming the film on the prescribed location on the substrate.
For instance, if several droplets are formed with very small intervals along a line, the partial pressure in the vicinity of the droplets formed in the outermost edge of the line is lower in the outer side where there are no droplets, and higher in the inner side where there are other droplets, resulting in an uneven partial pressure. This is caused since the solvent vapor originating from the adjacent droplet increases the partial pressure of the gas in the side where there are other droplets in the vicinity of the last droplet in line.
In many electronic devices, functional films are used after undergoing patterning. Constraints in the employed material or specific conditions are required when forming organic crystalline films with a vacuum deposition and the like. The resist tolerance of the organic films is low. Therefore, applying normal patterning with photolithography and etching is difficult.
In contrast, if the crystalline films are formed with the inkjet method, then the formation of the patterned organic crystalline films become easier.
JP-A-11-40358 and JP-A-11-54272 are examples of related art.